What do you put more value on when buying a CCW holster, retention or deployment?

The three most comfortable holsters I have owned are two Galco brand OWB and 1 Wilson Combat IWB all without thumbreaks. All holsters fail to keep the gun from falling out when inverted so I'm replacing them all with quality holsters with thumbreak. It makes sense to me that retention takes priority over deployment for civilian use so here is your chance to persuade me otherwise.

Now before you flood the thread with photos of your favorite EDC in a friction holster inverted, consider I've already invested almost $200 in those Galco holsters alone that did not work for me.... what I'm after here is more about advice that I might have missed using friction holsters or why deployment might be higher priority than retention, not your favorite way to carry.